Steven Spielberg, Barack Obama, Stephen King, and Damon Lindelof were among the well-known figures paying tribute to Ray Bradbury, the author of such classics as Fahrenheit 451 and The Martian Chronicles who passed away today at 91.

“He was my muse for the better part of my sci-fi career,” Spielberg said in a written statement. “He lives on through his legion of fans. In the world of science fiction and fantasy and imagination he is immortal.”

The two men were mutual fans. Bradbury called Spielberg’s 1977 film Close Encounters of the Third Kind “the best film of its kind ever made.” He later visited the young director “to tell [him] what a genius he was. Spielberg told him that seeing the 1953 sci-fi classic It Came From Outer Space, which was adapted from a Bradbury story, inspired Close Encounters.

Stephen King, in a statement, noted Bradbury’s prolific output and praised the power of his works. “The sound I hear today is the thunder of a giant’s footsteps fading away. But the novels and stories remain, in all their resonance and strange beauty.”

Neil Gaiman wrote on his blog that Bradbury’s death had “knocked me for a loop,” and he promised a longer statement later. He also posted an essay he wrote that was originally printed in an edition of Bradbury’s The Machineries of Joy. “If you want to quote me, you can take anything you like from this, and add that he was kind, and gentle, and always filled with enthusiasm, and that the landscape of the world we live in would have been diminished if we had not had him in our world.

Prometheus and Lost writer Damon Lindelof tweeted, “Fahrenheit 451: The temperature at which my heart aches. We will miss you, Ray.”

But the tributes were not just confined to Hollywood writers and directors.

President Obama issued a statement saying, “His gift for storytelling reshaped our culture and expanded our world. But Ray also understood that our imaginations could be used as a tool for better understanding, a vehicle for change, and an expression of our most cherished values. There is no doubt that Ray will continue to inspire many more generations with his writing.